Pancreatic involvement is common and the injury progresses to pancreatic insufficiency (PI) in the majority of patients with cystic fibrosis (CF). Currently, there are no treatments to halt the progression of pancreatic disease in CF and the exact mechanisms leading to the destruction of pancreas are not well-understood. Two major obstacles until now have been inaccessibility of the pancreas in humans and lack of a suitable animal model. We produced pigs (Sus scrofa) with a targeted disruption of both cystic fibrosis transmembrane conductance regulator (CFTR) alleles. These animals had pancreatic lesions markedly similar to those found in humans with CF and their pancreas had an increased number of inflammatory cells and higher levels of a proinflammatory cytokine, IL-8. The goal of this project is to fully characterize the anatomical and physiological features of CFTR-/- pig pancreas and to utilize the data obtained from this model to shed light on the pathophysiology of pancreatic disease in humans with CF. We plan to reach our goal with the following Specific Aims: (1) determine the ontogeny of exocrine pancreatic lesions in CFTR-/- pigs;and (2) determine the role of CFTR in regulating exocrine pancreatic function in vivo and in vitro. The first aim will test the hypothesis that pancreatic disease in CF starts as acinar plugs in utero and progresses over time to acinar cell atrophy, duct dilatation, mucous cell metaplasia and fibrosis. The anatomical origins, disease progression and pathophysiological features of the novel porcine model of CF will be characterized using histopathology, enzyme expression, pancreatic cell markers and microarray gene profiling. The impact of inflammation on the development and progression of the pancreatic lesions will be explored. The second aim will test the hypothesis that CFTR is directly involved in pancreatic Cl- and HCO3- secretion. The role of CFTR in regulating the exocrine pancreatic function of pigs will be determined in vivo (analysis of fecal fat and chymotrypsin;collection of pancreatic fluid) and in vitro (primary porcine ductular epithelial cell cultures) using CFTR-/- and CFTR+/+ pigs. The objective of this application is to study the pancreatic pathophysiology in our novel swine model of CF and to better understand the pathophysiological mechanisms leading to pancreatic involvement in CF. Our long-term goal is to design innovative therapies to preserve pancreatic function and improve the quality of life, growth delay and malnutrition in CF. PUBLIC HEALTH RELEVANCE: Pancreatic involvement is common and the injury progresses to pancreatic insufficiency (PI) in the majority of patients with cystic fibrosis (CF). Currently, there are no treatments to halt the progression of pancreatic disease in CF and the exact mechanisms leading to the destruction of pancreas are not well-understood. The goal of this application is to fully characterize pancreatic involvement in our novel CF pig model and to better understand the pathophysiological mechanisms leading to PI in CF.